Many gas turbines are used for various applications ranging from those for general industries, such as electric power generation, to those for aircraft such as helicopters. In the gas turbine, power is generally obtained by jetting fuel at air, which has been compressed at a high temperature by a compressor, within a combustion cylinder to burn the fuel, thereby producing a combustion gas, straightening the combustion gas by stationary blades, and guiding it to moving blades, thereby rotating a turbine. In recent years, a high output and a high efficiency have been demanded of the gas turbine, and the temperature of the combustion gas guided to the stationary blades and the moving blades has tended to become higher.
However, the heat-resistant performance of the respective members exposed to the combustion gas, including the stationary blades and the moving blades, is restricted by the characteristics of their materials. Thus, if it is attempted to achieve the high output and high efficiency simply by raising the temperature of the combustion gas, a decrease in strength may be caused to the respective members such as the stationary blades and the moving blades. Under these circumstances, it has been customary practice to provide a cooling passage, intended for flowing a cooling medium such as air or steam, in the interior of each of the stationary blades and the moving blades. By so doing, it has been attempted to ensure heat resistance while cooling the stationary blades and the moving blades, and achieve the high temperature of the combustion gas, thereby increasing the output and the efficiency.
Turbulators for increasing the heat transfer coefficient are provided in the above cooling passage. These turbulators are arranged in multiple stages obliquely at a predetermined angle with respect to the extending direction of the cooling passage, that is, arranged to cross the flowing direction of the cooling medium, thereby causing turbulence to the cooling medium flowing into the cooling passage, and also forming secondary flows running along the turbulators. By this action of the turbulators, the amount of heat exchange with the wall surface of the cooling passage is increased to increase the heat transfer coefficient and perform the cooling of the blades efficiently.
Such a conventional blade cooling structure of the gas turbine is disclosed, for example, in Patent Document 1.    Patent Document 1: JP-A-2005-147132